众所周知，我们的核心生产
数据库通常都是在归档模式下运行的，更不用说还配置DG环境的了。开启归档，并保证所有归档不丢失，就能保证我们对数据库所做的任何修改不会丢失，归档日志可谓是恢复的根本，如果丢失归档，那么即使RMAN功能再强大，也无法对丢失的数据进行恢复。所以我们通常配置的RMAN策略就是全备+归档+控制文件自动备份。这里的归档不是指数据库创建以来生成的归档(那量也太大了)，而是当进行RMAN非一致性备份时新产生的那部分归档日志，用来保证数据库可以前推到一致性状态，这样才能顺利open数据库。以下的测试只是想说明归档日志对恢复数据的重要性，并没有用到RMAN来进行恢复。
测试一：归档日志健全未丢失
--连接到Oracle，确保是运行在归档模式下 [oracle@ora10g ~]$ sqlplus / as sysdba
SQL*Plus: Release 10.2.0.1.0 - Production on 8 13:46:53 2014
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production With the Partitioning, OLAP and Data Mining options
SQL> archive log list Database log mode Archive Mode --归档模式 Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 172 Next log sequence to archive 174 Current log sequence 174 SQL> set lin 130 pages 130 SQL> col name for a45 SQL> select file#,name from v$datafile;
FILE# NAME ---------- --------------------------------------------- 1 /u01/app/oracle/oradata/ora10g/system01.dbf 2 /u01/app/oracle/oradata/ora10g/undotbs01.dbf 3 /u01/app/oracle/oradata/ora10g/sysaux01.dbf 4 /u01/app/oracle/oradata/ora10g/users01.dbf 5 /u01/app/oracle/oradata/ora10g/example01.dbf
--创建测试表空间、用户、表 SQL> create tablespace zlm_test datafile '/u01/app/oracle/oradata/ora10g/zlm01.dbf' size 50m;
Tablespace created.
SQL> create user zlm identified by zlm default tablespace zlm_test;
User created.
SQL> grant connect,resource to zlm; --赋权限
Grant succeeded.
SQL> select file#,name from v$datafile;
FILE# NAME ---------- --------------------------------------------- 1 /u01/app/oracle/oradata/ora10g/system01.dbf 2 /u01/app/oracle/oradata/ora10g/undotbs01.dbf 3 /u01/app/oracle/oradata/ora10g/sysaux01.dbf 4 /u01/app/oracle/oradata/ora10g/users01.dbf 5 /u01/app/oracle/oradata/ora10g/example01.dbf 6 /u01/app/oracle/oradata/ora10g/zlm01.dbf --新增了6号文件作为测试表存放的物理介质
6 rows selected.
SQL> create table zlm.test1 as select rownum as id,object_name from dba_objects where rownum<=5;
Table created.
SQL> col object_name for a15
SQL> select * from zlm.test1;
ID OBJECT_NAME ---------- --------------- 1 ICOL$ 2 I_USER1 3 CON$ 4 UNDO$ 5 C_COBJ#
--查看当前online日志文件状态 SQL> select group#,status,archived from v$log;
GROUP# STATUS ARC ---------- ---------------- --- 1 INACTIVE YES 2 INACTIVE YES 3 CURRENT NO --当前日志组为3，未归档
--归档当前日志（多次） SQL> alter system archive log current;
System altered.
SQL> alter system archive log current;
System altered.
SQL> alter system archive log current;
System altered.
这里进行了3次归档当前日志文件的操作，目的是使online日志被刷新，强制其归档，写到归档日志中去，因为我们要测试的是归档，否则恢复文件时，会自动去online日志中查找，即便是非归档模式，只要online日志还未被刷新，依旧是可以恢复的
SQL> select group#,status,archived from v$log;
GROUP# STATUS ARC ---------- ---------------- --- 1 INACTIVE YES 2 INACTIVE YES 3 CURRENT NO --虽然看起来和刚才上一步一致，但此时其实已经把第3组online日志刷新掉了
--保险起见，再归档一次（可选） SQL> alter system archive log current;
System altered.
SQL> select group#,status,archived from v$log;
GROUP# STATUS ARC ---------- ---------------- --- 1 CURRENT NO 2 INACTIVE YES 3 ACTIVE YES --现在新一轮的第3组的日志也已经归档了
--一致性关闭数据库，在OS级别删除测试文件datafile 6 SQL> shutdown immediate
Database closed. Database dismounted. ORACLE instance shut down. SQL> ! [oracle@ora10g ~]$ cd $ORACLE_BASE/oradata/ora10g [oracle@ora10g ora10g]$ ll -lrth total 1. |